This invention relates to two-state Hall element sensors and more particularly to such sensors providing visual indication of their state. Two-state Hall element sensor devices are commercially available and are used as proximity sensors in manufacturing machinery, safety interlocks and intrusion alarm systems. Such two-state sensors are sometimes referred to as Hall element switches, because they provide an electrical output signal only when the ambient magentic field exceeds a predetermined value.
From one to many such sensor devices are employed in various manufacturing equipment and other complex systems. It is common practice to use a magnet in conjunction with the sensors, the magnet being mounted to a moving object relative to the sensor device, so that when the magnet is within a predetermined range of the sensor device, the Hall element sensor device changes state and produces an electrical signal. The electrical signal is connected to other devices in the system, e.g., for counting the magnet pass-bys, for actuating an alarm or for activating work stations along a production parts conveyor.
The installation, routine periodic adjustment and trouble shooting of the sensors in the system requires the use of special test equipment, or reliance on the responding devices of the system to be actuated by each sensor, to determine under various conditions of sensor device mounting, position of magnets, and electrical power supply, which of the two sensor states exist. These procedures are often inconvenient and time consuming.
It is an object of the present invention to provide in a two-state Hall element proximity sensor device a visual means for indicating at any time which of the two states exists, toward making installation, routine use, and maintenance of the device more efficient, reliable and convenient.